Adaptive actions of young infants in the task of reaching for objects.

Although several studies have investigated how movement trajectory and arm/hand configuration are adjusted to environmental affordances, the influence of specific object properties on early adjustments has not been studied. In this study, we aimed to determine the combined effect of object size and rigidity on reaching movements in young infants. Sixteen typically developing infants were assessed at 4, 5, and 6 months of age. The infants were presented with four objects: two soft and two rigid, which were either small or large. The results indicate that with age reaching movements became straighter, the arm control during the final phase was improved, and the grasping success increased. Object size and rigidity collectively influenced the proximal adjustments, grasping, adjustment time, and the number of movement units. The results suggest that early in the infants are able to modify their movement strategies based on object affordances.